4:12 edifying. The gifts are all to be used for “edifying”—that is, “building up”—the body of Christ, both individually and corporately, adding stones to the building, as it were (Ephesians 2:22) and also strengthening the individual members.

4:13 unity of the faith. See note on Ephesians 4:3. Also note Romans 16:17-18.

4:13 and. “And” could better be rendered “even.” That is, the unity of the faith is essentially synonymous with “the knowledge of the Son of God.”